Increase of intracerebral pressure (ICP) during laparoscopic surgery has known to be associated with positional changes. Optic nerve sheath diameter (ONSD) has correlation with ICP and ultrasonographic measurement of optic nerve sheath diameter (ONSD) is known to be a noninvasive and rapidly applicable technique for evaluating ICP. The aim of this study is to investigate the change of ONSD according to the positional change during laparoscopic surgery.